Tire tread depth is a safety issue. Worn tires have little traction especially on wet roads. Visual inspection or tire tread depth measurements may be made to determine the amount of tread left on a tire. However, tires may wear down to an unsafe level unless checked with sufficient frequency so that the rate of tire tread wear can be properly ascertained for a good prediction of the end of useful tire service.
Tire tread depth also affects fuel economy. Vehicular fuel economy is directly affected by resistance to movement, including rolling resistance. Underinflated tires increase rolling resistance and increase fuel use per unit distance. Tire tread depth measurements and wear patterns reveal issues in maintaining tire inflation at proper levels.
There are several devices for measuring tire tread depth including handheld devices and drive-over devices. These are useful and convenient but there remains a need for improvement.